Field of the Invention
The present invention generally relates to a chip package. More particularly, the present invention relates to a chip on film package.
Description of Related Art
In semiconductor production, the manufacturing of integrated circuits (IC) can be divided into three different stages, namely, a wafer fabrication stage, an integrated circuit fabrication stage and an IC packaging stage such as applying a chip-on-film (COF) package.
To increase the dissipation of heat from a chip of a COF package, a heat dissipation sheet is normally attached to a top surface of the base film to cover the whole chip or attached to a bottom surface of the base film opposite to the chip using thermal conductive glue after the chip is electrically connected to the film via bumps. Conventionally, during the process of attaching the heat dissipation sheet on the film for covering the chip, it is hard to make the heat dissipation sheet and the chip tightly attached together, so air gap usually exists between the chip and the heat dissipation sheet. As such, the air trapped between the chip and the heat dissipation sheet would expand during the subsequent thermal process, which may cause the heat dissipation sheet separating from the chip and reduce the reliability of the chip package. Moreover, since the heat conductivity of air is rather low, the air trapped in the space between the chip and the heat dissipation sheet would also affect the efficiency for heat generated from the chip to be conducted to the heat dissipation sheet.